The cumulative effects of cold ischemic time and older donor age on liver graft survival

INTRODUCTION: To provide greater equity among those awaiting a liver transplant, expanded geographic sharing of cadaveric organs has been proposed. A potential unintended consequence could be an increase in cold ischemia time (CIT), which may be deleterious to organs from older donors. This study sought to quantify the relative risk (RR) associated with increased CIT among older donors. METHODS: A retrospective study examining 18,787 liver transplants within the United Network for Organ Sharing database from 2002 to 2006 was performed. Cox Regression analysis was used to model the RR of graft loss with respect to increased CIT among older donors (>60 years) relative to younger donors (<60 years), while controlling for multiple donor and recipient characteristics. RESULTS: Relative to younger donors with minimal CIT (<6 h), a 73.0% increase in the risk of graft loss was observed for older donors with a CIT between 8 and 10 h, a 56.9% increase for CIT between 10 and 12 h, and a 92.7% increase for a CIT of 12 or more hours. Additionally, the RR of graft loss for older donors with minimal CIT (<6 h) was greater than the RR for younger donors with a CIT between 0 and 12 h. CONCLUSION: The additive effects of increased donor age and cold ischemic time greatly impair graft survival. Quantification of the adverse nature of increasing CIT as a potential consequence of wider geographic organ sharing should be considered as allocation policies are modified to improve recipient equity in the face of an aging donor pool.